Basic knowledge of the mechanism of enzymes metabolizing alcohol is essential for understanding the pathology of alcoholism. We intend to continue our investigations on the structure and function of liver alcohol dehydrogenase (LADH) and its isoenzymes in studies of the amino acid sequences (in collaboration with H. Jornvall at this institute) and X-ray crystallographic structure (in collaboration with C.-I. Branden at Uppsala Univ.) and the interaction with coenzyme, substrates and inhibitors. Particular emphasis will be put on investigating the ADH and its iso-enzymes from human liver and other organs. In order to separate the isoenzymes we are going to use an arsenal of methods, including extraction, salt and alcohol fractionation, chromatography on cellulose, on Sephadex ion exchangers, or affinity chromatographyon e.g. AMP- and ADP-Sepharose. Electrophoretic methods will be used for separation and control of homogeneity of the enzymes from different organs from man and animals. Concerning the substrate specificity very much remains to be done concerning not only alcohols but also hydroxysteroids, hydroxy-fatty acids and others. Spectrophotometry and fluorimetry offer excellent methods for this purpose. Further work on synthetic inhibitors, of which 4-substituted pyrazoles have proved to be especially powerful and interesting, is of profound importance for clearing up the working mechanism of the liver alcohol dehydrogenase. The reaction velocities with different substrates and inhibitors, both in varied concentrations, can be determined by many different methods: Spectrophotometry, fluorimetry, chemical analyses of reaction products after different times, and others. For very fast reactions the "rapid flow" methods are of great value.